The present invention relates to a radial anchoring system for traction elements of a flexible tubular structure which is achieved by axially pressing a portion of the tubular structure on a shoulder or flange after passage through an opening provided in a rigid wall or mating flange. In this text, to simplify the disclosure of the invention, the term "sleeve" will be used to define the flexible annular structure and the term "bead" will define the end of the sleeve which has a larger diameter than that of the sleeve and which abuts the rigid wall, hereinafter called "mating flange."
Sleeves with a flexible bead are known wherein the bead generally has an internal armature, i.e. embedded in the rubber, of annular form, composed of high-modulus rubber, a textile ply, a textile or metal strand, or a flexible spring. This type of reinforcement is adopted to render the bead deformable to permit mounting mating flanges after manufacture of the sleeve, by forcing the bead through the bore. The major drawback of these systems is the requirement of a pinching of the flat flange between two planes, according to the device proposed by, for example, the Societe Kleber Industrie for Dilatoflex NT expansion sleeves (technical dossier 79-BA1), or by the use of a machine form for a rigid part to abut a diameter inside this deformable bead, as proposed, for example, in the air suspension diaphragms described in the French Patent FR 72.02268, or in the expansion sleeves described in French patents FR 2 280 853, 2 033 789 or FR 2 006 730.
These sleeve systems with flexible beads require mounting techniques which often cause a strong stress concentration at the end of the mating flange, which can go as far as damaging or even destroying the sealing function. Hence, the usual sleeves with flexible beads can only be used for moderate service pressures. To overcome these drawbacks, it has been proposed in, for example, U.S. Pat. No. 2,998,986 to provide rigid sleeves having large contact areas with the flange. This is in fact the solution adopted by Kleber Industrie for the Endflex system described in the Performer AD10 pipe catalog, page 4 or Dilatoflex K expansion sleeves described in catalog FC175-18, June 1984.
All these devices have high rigidity and are usually built with metal elements. Because of their design, rubber is compressed over a large contact surface area which improves stress distribution and reduces creep sensitivity, thus providing a better guarantee of tightness and the possibility of utilization at high service pressures.
However, due to their rigidity, these beads have the disadvantage of making it impossible to mount one-piece mating flanges after a manufacturing of the sleeve. Thus, it is necessary to mount the mating flanges during production and to vulcanize the sleeve thus equipped with these metal parts, which considerably adds to the weight and volume.
In addition, mating flanges are no longer demountable as shown by the Stenflex and General Rubber catalogs. The sleeve manufacturer must hence keep a large inventory on hand so that sleeves equipped with flanges conforming to the various standardized connections are available.
A sleeve with demountable flanges is described in patent French Pat. No. 2447512 but the beads are rigid and have reinforcing collars separate from the sleeve. The proposed solution, which consists of surrounding the collar by a U-shaped rubber form, requires the use of a very complex mold.
As can be seen from the above analysis, no solution has been proposed which enable the requirements of anchoring quality (to withstand high service pressures or pulls), tightness of bonding, and ease of mounting on a flange or rigid shoulder to be met.
Hence, an object of the invention resides in providing an anchoring device which offers the advantages of the two types of known beads without accompanying disadvantages as encountered in the prior art. According to the present invention, an anchoring is obtained by a bead having a large contact surface on the flange or shoulder, while offering a flexibility so as to allow for a bending for passage of the bead through the bore.
Thus, the invention permits a simpler manufacturing of the sleeve by eliminating the weight and volume problems required by the necessity, in previously known solutions, of mounting the mating flanges during manufacture. Moreover, this represents an essential saving and considerably reduces the need to maintain a large parts inventory due to the various standardized connections since the same range of sleeves can be equipped with the various types of commercial or customized mating flanges at the time of delivery. Management and marketing of the sleeves is thus greatly facilitated and delivery times are considerably reduced.
According to the present invention, a radial anchoring device is provided on at least one end of a flexible tubular structure or sleeve such as a rubber hose, deformable collar, expansion joint, or suspension diaphragm by abutting a shoulder or mating flange after passing through an opening or bore made in a rigid wall, with the flexible tubular structure or sleeve having at least one bead reinforced by an armature embedded in the rubber, which is one-piece and rigid at the time it is manufactured, but mechanically divisible at the time of mounting into predefined sections or segments to allow the bead to bend so it can slide into the bore of the rigid wall without altering, after a return to a plane shape, the radial rigidity which confers on the bead the necessary strength for proper operation in service when compressed between the flange and the mating flange.
Advantageously, the rigid bead-reinforcing armature of the present invention may be of a highly rigid metal or plastic hoop with the armature being predivided into at least four sections or segments by predivision zones with a minimum thickness of 0.05 mm.
At the time the sleeve is manufactured, the rigid armature is in a one-piece form which facilitates a handling and positioning thereof in the mold. At the end of the vulcanization operation, the sleeve thus has a rigid bead. At this time or at the time of mounting in the mating flanges, the armature is mechanically divided into sections or segments by applying pressure in a vicinity of the predivision zones. The sections, or segments embedded in the rubber, are articulated with each other without damaging the reinforcing carcass of the sleeve and permit passage of the bead through the bore by bending the bead which has become flexible, with the bead reopening on the shoulder naturally after the mating flanges have been put in place. The bead, secured between the connecting flange and the mating flange or shoulder retains a radial rigidity equivalent to that of a bead having a one-piece armature by the self-squeezing effect.
The divisible armature is preferably made of a metal such as, for example steel, aluminum, Zamak, or any other material with a modulus greater than 1500 MPa.
It can be made of reinforced plastic or composite material provided the material allows a clean break in the predivision zones.
It can be a single material (metal, reinforced plastic, or composite) or be made with a central core of breakable material, molded inside a stronger material to force the break to occur in the desired area.
The armature, thus predivided into sections, or segments can be made by partial machining, by molding, or by forming depending on the workability of the material of which it is composed. At the time the sleeve is made, the armature can be placed in the bead either bare or covered with a ply of rubber mixture or of a fine textile material, the latter two possibilities having the advantage of preventing the carcass of the sleeve from being damaged by contact with the angles of the divisible armature.
The number of sections or segments is preferably between seven and thirteen, but it can be as high as permitted by the strength of the material and manufacturing economics.
The general shape of the sections is usually trapezoidal but other possibilities such as rectangular, triangular, lozenge, or double trapezoidal can be considered as nonlimitative examples; however, these latter shapes would complicate manufacture of the divisible armature but would not impede operation thereof.
The predivision zones are generally radially oriented but the divisible reinforcement function is not disturbed if the predivision zones have a slight inclination, of between 0.degree. and 40.degree. for example to the diametral plane.
The predivision zones more commonly are rectilinear but the zones may have the shape of the arc of a circle, any curve, or chevron. Their widths are between 5% of the width of the armature, to permit formation of gum bridges between the rubber mixtures surrounding them, and 50% of the width of the armature, so as not to render the armature fragile or too deformable.
The connecting part of the sections, before division, is preferably less than 25% of the thickness of the armature when metal materials are used but it can be as high as 90% to 95% of the thickness of the armature if a very breakable material is used wherein light pressure or a tap would be sufficient to cause breakage. The predivision zones are preferably located on the part of the armature which is on the bore size, but any other arrangement can be used.
The characteristics and variants of the invention will be better understood by reading the description hereinbelow with reference to the drawings, wherein: